Method and apparatus for processing photographic material

ABSTRACT

A method and apparatus for processing photographic material of the scavenger type where the used processing solution runs to waste. The direction and rate of flow of processing solution through any processing stage is the same as the direction and speed of the sensitized material transport through that stage, so that each part of the emulsion surface meets fresh solution in the first part of the processing stage and processing is continued with the same solution in the remaining parts of the processing stage. In this way processing is the same whether a long length or a single sheet of photographic material is processed.

United States Patent 2,587,350 2/1952 Maiwald, .lr.

Inventors Appl. No.

Filed Patented Assignee Priority METHOD AND APPARATUS FOR PROCESSING PI'IOTOGRAPHIC MATERIAL 7 Claims, 7 Drawing Figs.

US. Cl

References Cited UNITED STATES PATENTS Primary Examiner-Samuel S. Matthews Assistant Examiner-Robert P. Greiner Att0rneysWalter O. Hodsdon, Paul R. Holmes and Karl T.

Naramore ABSTRACT: A method and apparatus for processing photographic material of the scavenger type where the used processing solution runs to waste. The direction and rate of flow of processing solution through any processing stage is the same as the direction and speed of the sensitized material transport through that stage, so that each part of the emulsion surface meets fresh solution in the first part of the processing stage and processing is continued with the same solution in the remaining parts of the processing stage. In this way processing is the same whether a long length or a single sheet of photographic material is processed.

Patented April 13, 1971 2 Sheets-Sheet 1 N ENTORS EYS ERIC T. SMITH JOHN G. HOWE i ATTORN Patented Amman, 1971 3,515,101

2 Sheets-Sheet 2 22 v 011ml) F|G 7 ERIC T. SMITH JOHN G. HOWE x 2 IZVZTZQE BY I k fizx ATTORNEYS METHOD AND APPARATUS FOR PROCESSING PHOTOGRAPHIC MATERIAL The present invention relates to a method of processing photographic material and apparatus therefor.

It has been proposed to process photographic sheet materials by passing them over rollers which dip into a bath containing processing solution thereby applying the processing solution to the surface of a photographic material. It has also been proposed to effect the processing by passing the photographic material under such a roller thereby immersing it in the processing solution.

It has been further proposed that in order to economize on the amount of processing solution required, the bath containing said solution should have a shape such that the volume of solution held between the bath and the roller is small. This arrangement, however, has the disadvantage that exhaustion of the small volume of processing solution can lead to undesired effects, for example uneven processing.

It has now been discovered that by introducing processing solution into the bath at the side where the sheet material enters and at a rate sufficient to keep pace with the material by arranging for the solution to flow through the bath to an outlet at the side where the material leaves, each part of the photographic material is processed with equally fresh solution.

Accordingly, there is provided a method of processing photographic material wherein at least one processing solution is applied to a sheet or continuous length of photographic material from the surface of at least one roller, and/or by passing it under at least one roller, and which rollers dip into troughs which are fed with the processing solution. The processing solution is caused to flow through the troughs so that the time taken for the solution to travel through the troughs is substantially equal to the time taken for the leading edge of the photographic material to pass across the troughs.

The time taken for the processing solution to travel through the troughs may be measured by starting to introduce processing solution into the empty troughs and measuring the time taken for the front of the processing solution to reach the drainage hole at the far end of the last trough. It is, however, noted that this time may differ slightly from time taken when the apparatus is in actual continuous operation.

The processing solutions that may be used in the present process are any of the conventional photographic processing solutions for both color and black-and-white photographic materials, for example developer, activator, stop bath, fixer, stabilizer or rinse solutions.

An apparatus suitable for carrying out the present process may comprise at least one roller which dips into a trough adapted to be fed with a photographic processing solution wherein the processing solution is caused to flow through the trough or troughs so that the time taken for the solution to travel through the trough or troughs is substantially equal to the time taken for the leading edge of the photographic material to pass across the trough or troughs. The apparatus may be of the surface application type as described in British Specification Nos. 960,413 or l,066,9l3.

In order that the invention may be readily understood several forms thereof will now be described with reference to the accompanying drawings in which:

FIG. I is a vertical section through a part of a processing apparatus which applies a single processing solution by surface application to the photographic material;

FIG. 2 is a horizontal sectional view of the trough unit shown in FIG. I and with the rollers omitted to show the flow path of the processing solution;

FIG. 3 is a vertical section of another form of trough unit;

FIG. 4 and 5 each show photographic material passing through a single pair of rollers;

FIG. 6 is a vertical section through a part of a processing apparatus which applies a single processing solution to the photographic material by a dipping procedure;

FIG. 7 is a horizontal sectional view of the trough unit shown in FIG. 6 with the rollers omitted to show the flow path of the solution.

As illustrated in FIGS. 1 and 2 the apparatus comprises a pair of driven nip rollers l which control the speed of the photographic material through the apparatus, rollers 2 which are rotatably mounted and disposed horizontally and parallel to each other and are driven in the direction shown at a tangential surface speed which may be greater than that of the photographic material, free-running rollers 3, and driven nip rollers 4 rotating at the same speed as nip rollers 1. A trough unit 5 comprising troughs 6 having a shape complimentary to the rollers 2 is provided with a solution inlet 8 and an outlet 9 and means, such as valve V in the inlet, for controlling the rate at which the solution is introduced into the apparatus. Connecting troughs 7 connect the troughs 6 in series so that the processing solution can circulate from the inlet 8 through each trough and leave through the outlet 9 under the influence of hydrostatic pressure. The flow of the solution may be assisted by tipping the apparatus front'to back by suitable means, e.g. blocks, elevating screws, etc. (not shown) so that the last trough is below the level of the first.

FIG. 3 shows an alternative method of circulating the processing solution wherein the trough unit 10 is tilted as shown and wherein the solution passes from one trough to the next along the entire lengththereof as indicated.

In the drawings the applicator rollers are shown rotating in the direction in which the photographic material is moving. This is illustrated in FIG. 4 in which material 12 passes between roller 2 and a free-running roller 3 with the formation of a bead of solution 14 to the left of the roller 2. This can cause a squeeging effect leaving very little of the solution on the emulsion surface of the material. For this reason it may be desirable for one or more of the applicator rollers to rotate in the opposite direction (FIG. 5) in which more solution is left on the surface of the material.

Finally, in FIGS. 6 and 7, the photographic material 15 passes between driven nip rollers 16, into a guide 17 which dips below the surface of a processing solution 18 contained in the trough unit 20, between the nip of rollers 19 and through further guides and rollers, as shown, finally leaving the apparatus by passing through squeegee rollers 21. FIG. 7 shows the flow pattern of the solution 18 which enters at inlet 22, passes through each trough through connecting ducts 23 and leaves by outlet 24.

As an alternative to the free-running rollers shown and described above, stationary guides as described in British Specification No. 960,413 may be substituted therefor when it is desired to reduce back wetting, that is wetting of the upper surface of the photographic material being processed.

The troughs into which the rollers dip preferably have a shape such that the volume of solution held between the trough and the roller is small.

Using a developer stage comprising four A-inch diameter applicator rollers I5 inches long in an apparatus as illustrated by FIGS. 1 and 2 wherein the roller-trough gap is about 0.1 inch the time taken for solution to flow through the apparatus at a supply rate of 40 mls/min. was between 2 and 2% mins. depending on the rate of rotation of the rollers. Time of between 1% and 3% mins. could be achieved with pumping rates of 30 to 70 mls/min.

The applicator roller unit may be of the double roller applicator unit type in which pairs of rollers are arranged in contact and contrarotating. Such'units are described in British Specification No. 1,066,913.

While certain specific embodiments of the invention are shown and described, many modifications thereof are possible. The invention, therefore, is not to be limited to the precise details shown and described but is intended to cover all modifications coming within the scope of the appended claims.

We claim:

I. In the method of processing a strip of photographic material wherein the strip of material is fed across a bath of processing solution at agiven speed from one end of the path to the other and in such a manner that any given point on said strip material is contacted by processing solution at successive points across said bath as it moves thereacross, the steps of:

maintaining a volume of processing solution in said bath by continuously feeding fresh processing solution into the end of said bath where the strip material enters and out the other end where the strip material leaves; and regulating the rate of flow of the solution across said bath so that it is substantially equal to the speed at which the strip material is moved across said bath.

2. The method of processing a strip of photographic material as claimed in claim 1, wherein the strip of material is moved across said bath in a substantially straight line, and wherein the processing solution in flowing across the bath follows a substantially sinusoidal path underlying and extending along the path of said strip material.

3. The method of processing a strip of photographic material as claimed in claim 1 wherein the processing solution is initially introduced into said first end of the bath under pressure and its rate of flow across and out of the bath is encouraged by gravitation in the direction of travel of the strip material.

4. A photographic processing apparatus for processing an elongated strip of photographic material comprising in combination:

a plurality of troughs joined together in spaced parallel relation and arranged so that a volume of processing solution introduced into the first of the series of troughs will flow into and through successive ones of the troughs and be discharged from the last one of the series;

at least one rotatable roller extending longitudinally of each trough and having its surface dipping into the processing solution in its respective trough for guiding a strip of photographic material across said troughs in succession and applying processing solution to at least one surface thereof;

means for feeding a strip of photographic material across said troughs in succession at a given speed and in the direction of flow of said processing solution; and

means for continuously introducing-a processing solution into said first trough and regulating the rate of flow of the solution through said troughs so that the speed at which the solution moves from trough to trough is substantially equal to the speed at which the strip material is moved across said troughs.

5. A photographic processing apparatus for processing an elongated strip of photographic material comprising in combination:

a receptacle whose interior contains a plurality of parallel partitions extending transversely, and spaced apart along the length, of said receptacle to provide a plurality of troughs joined together in spaced parallel relation and arranged so that a volume of processing solution introduced into the first of the series of troughs will flow into and through successive ones of the troughs and be discharged from the last one of the series, said receptacle being inclined downwardly in the direction of flow of said processing solution to enhance such flow from trough to trough;

at least one rotatable roller extending longitudinally of each trough and having its surface dipping into the processing solution in its respective trough for guiding a strip of photographic material across said troughs in succession and applying processing solution to at least one surface thereof;

means for feeding a strip of photographic material across said troughs in succession at a given speed and in the direction of flow of said processing solution; and

means for continuously introducing a processing solution into said first trough and regulating the rate of flow of the solution through said troughs so that'the speed at which the solution moves from trough to trough is substantially equal to the speed at which the strip material is moved across said troughs. 6. A photographic processing apparatus for processing an a plurality of troughs joined together in spaced parallel relation;

means placing opposite ends of adjacent troughs in communication with one another so that a processing liquid introduced into one end of the first trough will flow longitudinally through successive ones of said troughs in a sinusoidal manner under the influence of hydrostatic pressure;

means for introducing a processing solution into the end of the first trough remote from the end thereof in communication with the second trough;

means for draining the processing solution from the end of the last trough remote from the end thereof in communication with the trough adjacent thereto;

at least one rotatable roller extending longitudinally of each trough and having its surface dipping into the processing solution in its respective trough for guiding a strip of photographic material across said troughs in succession and applying processing solution to at least one surface thereof;

means for feeding a strip of photographic material across said troughs from said first trough to the last trough in succession at a given speed; and

means for continuously feeding processing solution into said first trough and regulating the rate of flow of the solution through said troughs so that the time taken for a given unit of volume of the processing solution to travel through said troughs from the point of introduction in the first trough to the drain in the last trough is substantially equal to the time taken for a given point on the strip material to move across all of said troughs;

7. A photographic processing apparatus as set forth in claim 6, wherein said means for regulating the rate of flow of the solution through said troughs includes means for tilting the plurality of troughs downwardly in the direction of movement of said strip material so that gravity aids the flow of the solution from trough to trough. 

2. The method of processing a strip of photographic material as claimed in claim 1, wherein the strip of material is moved across said bath in a substantially straight line, and wherein the processing solution in flowing across the bath follows a substantially sinusoidal path underlying and extending along the path of said strip material.
 3. The method of processing a strip of photographic material as claimed in claim 1 wherein the processing solution is initially introduced into said first end of the bath under pressure and its rate of flow across and out of the bath is encouraged by gravitation in the direction of travel of the strip material.
 4. A photographic processing apparatus for processing an elongated strip of photographic material comprising in combination: a plurality of troughs joined together in spaced parallel relation and arranged so that a volume of processing solution introduced into the first of the series of troughs will flow into and through successive ones of the troughs and be discharged from the last one of the series; at least one rotatable roller extending longitudinally of each trough and having its surface dipping into the processing solution in its respective trough for guiding a strip of photographic material across said troughs in succession and applying processing solution to at least one surface thereof; means for feeding a strip of photographic material across said troughs in succession at a given speed and in the direction of flow of said processing solution; and means for continuously introducing a processing solution into said first trough and regulating the rate of flow of the solution through said troughs so that the speed at whiCh the solution moves from trough to trough is substantially equal to the speed at which the strip material is moved across said troughs.
 5. A photographic processing apparatus for processing an elongated strip of photographic material comprising in combination: a receptacle whose interior contains a plurality of parallel partitions extending transversely, and spaced apart along the length, of said receptacle to provide a plurality of troughs joined together in spaced parallel relation and arranged so that a volume of processing solution introduced into the first of the series of troughs will flow into and through successive ones of the troughs and be discharged from the last one of the series, said receptacle being inclined downwardly in the direction of flow of said processing solution to enhance such flow from trough to trough; at least one rotatable roller extending longitudinally of each trough and having its surface dipping into the processing solution in its respective trough for guiding a strip of photographic material across said troughs in succession and applying processing solution to at least one surface thereof; means for feeding a strip of photographic material across said troughs in succession at a given speed and in the direction of flow of said processing solution; and means for continuously introducing a processing solution into said first trough and regulating the rate of flow of the solution through said troughs so that the speed at which the solution moves from trough to trough is substantially equal to the speed at which the strip material is moved across said troughs.
 6. A photographic processing apparatus for processing an elongated strip of photographic material comprising in combination: a plurality of troughs joined together in spaced parallel relation; means placing opposite ends of adjacent troughs in communication with one another so that a processing liquid introduced into one end of the first trough will flow longitudinally through successive ones of said troughs in a sinusoidal manner under the influence of hydrostatic pressure; means for introducing a processing solution into the end of the first trough remote from the end thereof in communication with the second trough; means for draining the processing solution from the end of the last trough remote from the end thereof in communication with the trough adjacent thereto; at least one rotatable roller extending longitudinally of each trough and having its surface dipping into the processing solution in its respective trough for guiding a strip of photographic material across said troughs in succession and applying processing solution to at least one surface thereof; means for feeding a strip of photographic material across said troughs from said first trough to the last trough in succession at a given speed; and means for continuously feeding processing solution into said first trough and regulating the rate of flow of the solution through said troughs so that the time taken for a given unit of volume of the processing solution to travel through said troughs from the point of introduction in the first trough to the drain in the last trough is substantially equal to the time taken for a given point on the strip material to move across all of said troughs;
 7. A photographic processing apparatus as set forth in claim 6, wherein said means for regulating the rate of flow of the solution through said troughs includes means for tilting the plurality of troughs downwardly in the direction of movement of said strip material so that gravity aids the flow of the solution from trough to trough. 